Magnetic break-switch.



G. E. PALMER.

MAGNETIC BREAK SWITCH.

APPLICATION FILED MAY 10| 1912.

1,084,104, Patented Jan. 13,v 1914.

3 SHEETS-SHEET l. s? il) b l D 3 *i I. l .E

WM gm G. E. PALMER.

MAGNETIC BREAK SWITCH.

APPLICATION HLBD MAY 1o, 1912.

1,084,104. Patented Jan. 13, 1914.

3 SHEETS-SHEET Z.

f 1 a w 1 1 1@ @S48 52 g) @f l G. E. PALMER.

MAGNETIC BREAK SWITCH.

APPLICATION FILED MAY 1o, 1912.

Patented J an. 13, 1914 3 SHEETS-SHEET 3.

dam/WM UNITED STATES PATENT oEEicE.

GRANVILLE'E. I LHER, 0F ASSIGNOB 10 THE PALMER ELECTRIC ILNUFACTUBINGconm, F BOSTQIH, IASSACHUSETIS, A CORPO- Barron or nanna nenne'xanax-SWITCH.

Specllcationioflietters Patent.

Application nled la 10, 19B. Serial lo. 896,458.

Patented Jan. 1 3, 1914.

Toall'whomtmcyconcem:

Be it known that LGR'ANvmLa Elkann, a citizen of the United States, andresident of Brookline, in the county of Norfolk and I 5 State ofMassachusetts, have invented certain newand useful Improvements inMagnetic Break-Switches, of which the followi is a specification.

he present invention relates to magnetically operated break switches,and one of its objects is to provide a switch of this character having aplurality of lixed con'- tacts for, each pole, .and unequal number ofmovable contacts so arranged as to simultaneously make andsimultaneously break connection ata plurality of points of each pole.-Each pair of coactive contacts comprises a rigid contact and a flexiblelaminated conltact, and the movable contact of each pair is so movableas to avoid destructive gouging of the rigid contact by the laminatedcontact. The contacts areso arranged that the break occurs at thehighest point of the contacting surfaces in each case, thus .avoiding 26the burning of the'contacts byrv the electrlc arc which occurs at theinstant of breaking the metallic connection. The arrangement of thecontacts is also such that when the switch is opened every movablecontact de- `30 scribes an arc of a circle which the electric arc wouldnaturally be caused to assume by the' hot air current' produced thereby.

i The switch to whlch the present invention relates is provided withmechanical means 85 for locking it in closed ition.

The invention comprises means for causing vthe switch to openimmediately if for 'any reason it fails to close completely. In thisconnection an auxiliary swltch is pro- 40 vided which normally remainsclosed when the main switch is open and which isopened by the closingmovement of the main switch. The auxiliary switch remains closed durinthe greaterpart of the closing movement o 5 the main switch but` isopened ever so Jslightly in advan'ce of the closing of the main switch.The completion of the closing movementl of themain switch is thereforeeffected by the momentum which the moving parts acquire prior to theopening of the auxiliary switch. Mechanism is provided for holding openthe auxiliaryy switch after it has been opened b the closingmovement ofthe main switc until the main' switch has thereafter been opened nearly'to its limit of opening movement. If for any reason the main switchshould'not be completely closed after opening the auxillary switch, themoving elements return to their. initial open position, due partly togravity and partly to the force of a spring acting upon the lockingdevice, during .which opening movement the auxiliary switch, aspreviously explained, is held open for the purpose of enabling the'moving parts to recede to a suiciently distant p0- sitlon prior to theclosing. of the auxiliary switch to enable the moving elements toacquire' the necessary momentum during the subsequent closin movement tofully close. In the event of failure of the main switch to closeproperly when the controlling circuit is c oeed for that purpose, itimmediately opens and attempts once more to close,

Vwith such rapidity that it may operate as many as four or live timeswithin the usual period of time when al manually operated closing switchis held closed.

-Othet features of theinventionare here. inafter explained and areillustrated on the accompanying drawings which illustrate one form inwhich the invention may be embodied.

On the drawings: Figure l represents a Vfront elevation of the switch inclosed posi'- tion. Fig. 2 represents a left side elevation of the same,in which the opening magnet is broken away to expose the interiorstructure. Fig. 3 represents a wiring diagram relating to the switch.VFig. 4 represents a i central vertical section of the switch in openposition. Fig. 5 represents a vertical section of the mechanismintersected by broken line 5 of Fig. 2. Fig. 6 represents averticallsection through the mechanism intersected by broken line'6 ofFig. 2. Fig. 7 represents an elevation of the trip mechanism whichcontrols the auxiliary switch, the position of the parts correspondingto closed position of the main switch as shown by Fig. 2. Fig. 8represents a view similar to Fig 7, including the springs which act inone direction upon the moving parts. Fig. 9 represents an elevation ofthe locking member. Fig. 10 represents an elevation of the arm whichcarries the movable Contact of the auxiliary switch. Fig. 11 representsan elevation of a latch which is mounted upon the member shown by Fig.10. Fig. l2 represents a lever which is acwith the contacts 13 and 15.

tuated by the armature of the closing magnet to transmit movement toopen the auxiliary switch. Fig. 13 represents a perspective view of oneof the movable units of the main switch,

The same reference charactersl indicate the same parts wherever theyoccur.

Referring first to Figs. 1, 2 and 3, the main feed wires are indicatedat 10 and 11. These wires are connected respectively to fixed contacts12 and 13. A fixed contact bearing special relation to contact 12 isindicated at 14, while a similar fixed contact indicated at 15 issimilarly disposed with relation to the contact 13. Conductors 16 and 17connected respectively to the contacts 14 and 15 lead to the pointswhere the main current is to be' used. Fig. 3 includes a plurality ofsymbols 18 which represent incandescent lamps in circuit with theconductors 16 and 17.

A movable switch unit such as that shown by Fig. 13 is used to formconnection between the stationary contacts 12 and '14,

. and a similar unit is used to form connection between the contacts 13and 15. These two movable switch units are substantially identical inconstruction, and a description of one will be sufficient for both.

A laminated movable contact 20 is affixed to an oscillatory carrier 21in position to engage one of the stationary contacts, while a similarlaminated movable contact 22 likewise afiixed to the carrier 21 is somounted as to cooperate with the other stationary contact. The movablecontacts 20 and 22 in the one case coperate respectively with thecontacts 12 and 14, while in the other case they cooperate respectivelyThe movable contacts 20 and 22 are electrically connected with eachother at all times by a metallic member 23, but the members 20, 22 and23 are insulated from the carrier 21. Each pair of coactive contacts isprovided with a spark tip 24 which prolongs the metallic connection whenthe switch is opened. These spark tips are movable with and electricallyconnected with the contacts 20 and 22 but a are insulated from thecarriers 21.

The two movable switch units are aflixed upon a rockshaft 25 so thatthey move in unison to open and close the line across the gap betweenthe stationary contacts. The sparktips are, as usual, adapted to engagethe stationary contacts when the switch is closed, and to remain incontact for a short space of time after the movable contacts 20 and 22have been retracted from their respective stationary contacts. Thesesparktips may be omitted, but it is to be understood that when used,they constitute, in effect, the longest or highest leaf of the brush,and the claims are to be read with this understanding.

The rockshaft 25 carries the armature 26 of the main closing magnetwhose core is indicated at 27. The winding of the closing magnet isindicated at 28. As shown by Fig. 4, asetscrew 29 is used to affix thearma- `ture tothe rockshaft. Two non-magnetic members 30 are aiiixed tothe upper end of the armature 26 in lsuch manner as to leave a spacebetween them as shown by Fig. 1. A roller 31 extends across this spaceand its ends are mounted in bearings in the nonmagnetic members. Theroller engages a locking latch 32, which is mounted upon a pivot stud33. lVhen the armature is moved to close the main switch, the roller 31engages the surface 34 of the locking latch and lifts the latch againstthe tension of a spring 35. The latch is notched to provide a shoulder36 for engaging the roller to hold the switch in closed position.

The locking latch is lifted to release the armature by a solenoid whosewinding is indicated at 37. This solenoid is mounted upon the armature26 in such manner that its weight tends to open t-he main switch. Themagnetizable core of the solenoid is indicated at 38. It is aflixed tothe lower end of a non-magnetic rod 39 which has a tip 40 ofnon-abrading material. The tip is adapted to strike the surface 34 ofthe locking latch to lift the same. The members 38, 39 and 40 constitutea movable unit which is loosely fitted so as to slide in a tube 41 whichextends through the winding 37. A pin 42 in the lower end of the tubeprevents the core from dropping out of the tube. The disposition of thesolenoid with relation to the locking latch is such that the core .38 islifted a considerable distance before the tip 40 strikes the latch, thusenabling the moving element to acquire suicient momentum to strike ahammer blow on the latch which will surely lift the latch to therequired extent. It will be observed that the axis of the core ofthesolenoid is tangential to an arc about the axis of the rockshaft 25.From this it follows that the upward thrust of the solenoid core againstthev locking latch causes a reactive counter thrust in the directionwhich forces the main switch to open position. No other force is appliedto the armature or to the movable elements of the main switch foropening the switch. This action of the solenoid, its weight, and thedownward pressure of the spring 35 on the locking latch, are the threeforces by which the main switch is opened. The first part of the closingmovement of the switch is opposed by only one of these forces, namely,the weight of the moving parts. The opposing force of the spring 35 doesnot occur until the roll 31 strikes the locking latch; but at that timethe moving parts have acquired their maximum momentum, and, furthermore,the direction in which thc .trolled by an auxiliary switch whose movableconta-ct is indicated at 43. This contact is carried by, but insulatedfrom, an oscillatory arm 44. The switch member 43 bridges across fromone stationary contact 45 to a similar stationary contact 46. Referringto Figs. 2 and 4, the mechanical connection indicated at 47 issufficiently loose to enable the movable contact 43 to adjust itself tothe stationary contacts. As shown by Fig. 3, one terminal of the winding28 is connected to the stationary contact 45 of the auxiliary switch.The other terminal of the winding 28 is connected to a binding post 48from which a conductor 49 runs to one stationary contact 50 of amanually operattive switch; The other stationary contact 46 of theauxiliary switch is connected by a conductor 51 with a binding post 52from which a conductor 53 runs to the stationary contact 13 of the mainswitch, on the side which is connected with the feed wire 11.

A conductor 54 runs from the stationary contact 12 to the movable member55 of the manually operative switch.` This switch is normally held open,as shown, by a spring 56, The movable element 55 is mounted upon a pivot57 and is provided with a handle 58. When the movable member 55 istilted to the left it engages the stationary contact 50, but when it istilted to the right it engages a stationary contact 59 from which aconductor 60 runs to a binding post 61. From the binding post aconductor 62 runs to one terminal of the solenoid winding 37, the otherterminal,l of that winding being connected by a conductor 63 with one ofthe contacts of the movable switch unit which coperates with thecontacts 13 and 15. As shown by the diagram, this conductor 63 isconnected directly to the base of the sparktip 24. Referring once againto the auxiliary switch, a spring 64 acting upon the arm 44 normallyholds the switch member 43 'against the contacts 45 and 46. Theauxiliary switch is thus h eld closed" v'hen the main switch is open.

The operation of the switch thus far described is as follows: Assumingthat the switch is open. as shown by Fig. 4, a circuit is closed throughthe closing magnet by tilting the handle 58 from its neutral position tothe left to place the member 55 in engagement with the contact 50. Thecurrent comingy from vfeed wire 10 follows conductor 54, switch member55, contact 50, conductor 49, bindingpost 48. closing coil 28,stationary contact 45, auxiliary switch 43, stationary contact 46,conductor 51, binding post 52, conductor 53, contact 13, to return wire11. If the pull of the closing magnet is-suilicient to carry the roll 31past the shoulder 36, t-he main switch will be locked in closed positionwith the cont-acts 20 and 22 against the contacts 12 and 14 on the onesideand with the contacts 20 and ..22

against the contacts 13 and 15 on the other side. Current from feed wire10 is thus transmitted through contact 12 to contact 20, to metallicmember 23, to contact 22, to cont-act 14, to conductor 16, to lamps 18,to conductor 17, to contact 15, to contact22, to metallic member 23, tocontact 20, to contact 13, to return wire 11. When the manually operatedswitch is released it is automatically opened and held in its neutralposition by the spring 56, thus breaking the circuit at that pointthrough 'the winding 28 of the closing magnet. The circuit throu h theclosing magnet is, however, otherwise roken by the auxiliary switch 43,which, as previousiy stated, is opened slightly before the complet-ionof the closing movement of the main switch. The mechanism for operatingthe auxiliary magnet is shown by Figs.V 4 to 12 inclusive.

A lever 65 is mounted upon the hub of the locking latch as shown by Fig,6. This lever has a nger`66 (see Fig. 12) which ism adapted to engagethe arm 44 of the auxiliary switch. A finger 67 of this lever is adaptedto be engaged by a member 68 affixed to one of the non-magnetic members30 at the upper end of the armature 26. T he member 68 engages thefinger 67 slightly before the main switch is closed, thus rocking theleverv 65 about the hub of the lockingllatch and causing the finger 66toretract the auxiliary switch from the stationary contacts. The member68, as shown, is in the form of a disk ,and has' an eccentric stem69`which' extends through the member 30. `This stem is screw-threaded,and, as shown by Fig. 1, is provided with a clamping nut 7 0 and bindingnut 71 whereby it is held in the desired position. The disk may beturned about thel axis of its stem to cause it to actuate the lever 65sooner or later as desired i-with reference to the closing of the mainswitch. So long as the main switch is .held closed by the locking latchthe disk 68 switch to move nearly to its maximum open position beforepermitting the auxiliary switch to close the circuit ag'un through the50 rise, thus further opening the tion during opening movement-,of themain switch is shown best by Figs. 4, 5 and 7.

5 The swinging arm 44 ofy the auxiliary switch is mounted upon a pivotpin 72, and it carries a short pivot pin 73. A trip latch 74 (see Fig.11) is pivotally mounted upon the pin 73 and is thus carried by the arm44 in the relation shown by F igs, 4, 5 and 7. The trip latch 74 has aslot 75 and a vnose 76. The slot 75 is occupied by the pivot pin 72 andrenders the latch capable of a short movement about its individual pivot73, while the pin limits such movement. The nose 76 is adapted tocoperate with a nose 77 formed upon the locking latch 32. (See Fig. 9)..A spring 78 (see Figs. 5 and 8) normally presses the latch 74 toward the23 locking latch 32. The two noses 76 and 77 are so related as to occupythe positions shown by Fig. 4 when the main switch is open and when theauxiliary switch is closed. When the main switch is closed the lockinglatch 25 is lifted, thus causing the nose 77 to move downwardly; and atthe saine time the auxiliary switch is opened, thus causing the nose 76to move upwardly. During this movement the latch 74 yields sufficientlyto enable the nose 76 to pass by theanose 77, after which the nose 76 issnapped forward by its spring to overlapping position, as shown by Figs.7 and 8. Now, therefore, (although the auxiliary switch is held open bythe lever 65 when the main switch is closed)y as soon as the main switchbegins to ope-n, the auxiliary switch is released by the lever 65. Whenthe auxiliary switch starts to close, the nose 76 moves down upon thenose 77 and the closing movement of the auxiliary switch is therebyarrested. The locking latch 32, of course, cannot descend t-o its normalposition until the roll 31 has leftit.

L The locking latch therefore holds the auxiliary switch open untilafter the roll 31has passed out of engagement with the surface 34 of thelocking latch. The locking latch upon being pressed down to its normalposition by its spring 35 causes the nose 77 to auxiliary switch untilthe angular change permits the nose 76 to escape from the nose .77. The

auxiliary switch is thereupon closed by its spring 64, but this does notoccur until the main switch is at or near its maximum open position.

The operation just described is so rapid that the main switch may beautomatically openedY and closed four or tive times during the space oftime which would usually elapsewhile the manually operative switch isheld closed, and the moment-um gained by the main switch as the resultof being permitted to open nearly to its maximum' open position aftereach failure to close insures ultimate closing in the desired mannerbefore the manually operative switch is released unless there issomething radically wrong with the switch mechanism; and neither theswitch nor its auxiliary remains in a partially closed position.

The operation of opening the main switch after it has been closed inthedesired manner is as follows: When the manually operative switch ismoved to form connection between the movable contact 55 and thestationary contact 59, current flows from the main feed wire 10 overconductor 54, contact 55, contact 59, conductor 60, binding post 61,conductor 62, solenoid winding 37, conduct-or 63, spark tip 24, metallicmember 23, contact 20, contact 13, and return wire 1l. The solenoid core38 is thus drawn upwardly, and a hammer blow is struck upon the lockinglatch 32. The roll 3l is thus released, and the impact of the solenoidcore reacts upon the armature 26 in such manner as to tend to open themain switch. The opening force is augmented by the weight of thesolenoid, and is supplemented by the reaction of the spring 35 whichpresses l down the locking latch. The main switch is thus electricallyopened, but the auxiliary switch is held open, as before explained, bythe coperation of the noses 76 and 77 until the movable contacts of themain switch are widely separated from their respective stationarycontacts.

The important feature concerning the relation of the main switchcontacts is that the electrical break between the two contacts of eachpair of contacts occurs at the highest point of the contacting surfaces.lVhen the' break occurs, the current of hot air produced by the arc, ofcourse, rises; and in the present instance the upward travel of the arcfrom the highest point. of the contacting surfacescarries'the arc awayfrom the contacts instead of causing it to traverse the contactingsurfaces and burn them. This is especially important with reference-tothe laminated members, because it. avoids fusing the laminations to eachother and leaves the laminations capable of free movement relatively toeach other. The metallic breaks are simultaneous with reference to thecontacts 12 and 20, 13 and 20, 14 and 22, and 15 Aand 22; but the fourspark tips remain in l contacting surfaces of the laminated con-v causedto move in a direction away from the laminated contacts. It is obviousthat the tacts are removed from the coursebin which the electricalA arcstravel. The angles at which the contacting surfaces are disposed aresuch that there is ample space for the*` rupture of the burning arc whenthe connection is broken, the spark tips being movable laterally as wellas upward y and leaving an unobstructed space directly above eachburning arc.

There is slight flexure of the laminated contacts when the switch isopened and closed. The laminated ,members are disposed and moved in suchmanner that when .the switch is closed the contacting surfaces of thelaminated members are drawn slightly along the stationary contacts asdistinl guished from being pushed. This manner of closing the switch bydrawing the laminated contacts is preferred to a motion by which thelaminated contacts are moved point foremost, because the pressure of onecontact 'against another increases when the switch is closed.

Having dthus explained the nature of my said invention and described awayl of constructing and .using the same, although with- 80 loutattempting to set forth all the forms in which it may bemadeor all themodes of its use, what I claim is:

1. An electric switch having al plurality of fixed contactsout ofvertical and horizontal alinement, a plurality of connected, cooperativemovably supported cont-acts each having conducting members of differentlengths with the longestmember uppermost, and means for simultaneouslymoving the movable contacts into and out of Vengagement with the fixedcontacts, the fixed and` movable contacts being relatively so locatedthat the uppermost member of each movable contact is first to engage andlast to disengage its corresponding fixed contact,

' whereby unobstructed paths for the rise of the electric arcs areprovided.

2. A multipolar electric switch having for each pole a lurality of fixedcontacts out of vertical and) horizontal alinement, a plurality ofconnected, coperative pivotally supported contacts each havingconducting members of different lengths with the longest memberuppermost, and means for simultaneously moving the movable contacts intoand out of engagement with the fixed contacts,the'fixed and movablecontacts being relatively so located that the uppermost member of "eachmovable contact is first to,

engage and last to disengage its corresponding fixed contact, wherebyunobstructed paths for the rise of the electric arcs are pro-vided.

3. An electric switch havinga plurality of fixed contafpts and aplurality of movably supported connected coperative contacts,

each pair of coperative contacts mounted at indifferent hei htand in adifferent vertical plane With're erence to the other pair of contactsandwith their coperativ'e surfaces' at an angle to the horizontal plane,said movable contacts having conduct-ing members of different lengthswith the longest member uppermost, and means for simultaneously movingthe movable contacts into and out of engagement with the fixed contacts,the fixed and movable contacts being relatively so located that theuppermost member of each movable contact is first to engage and last todisengage its correspond-l ing fixed contact, whereby unobstructed pathsfor the rise of the elect-ric arcs are provided.

. 4. A multipolar electric switch having a plurality of fixed'contactsand a plurality of movably supported' connected coperative contacts foreach pole, each pair of coperative contacts mounted at a differentheight and in a different vertical plane with reference to the otherpair of contacts and with their coperativesurfaces at an angle to thehorizontal plane, said movable contacts having conducting members ofdifferent lengths with the longest member uppermost, and means forsimultaneously moving the movable contacts in arcs about a common axisinto and out of engagement with the fixed cont-acts in such'manner thatthe uppermost member of each movable contact is first to engage and lastto disengage its correspond'-v ing fixed contact, whereby unobstructedpaths for the rise of the electric arcs are provided.

5. An electric switch having a plurality o fixed contacts and aplurality of movably supported connected coperative contacts, each pairof coperative contacts mounted at a different heivht and in a differentvertical plane with re erence to the other pair of contacts and withtheir coperative surfaces at an angle to the horizontal plane, saidmovable contacts having conducting members of different lengths with thelongest member uppermost, and means for simultaneously moving themovable "contacts in arcs about a common axis into and out of engagementwith the fixed contacts in such manner that the uppermost member of eachmovable contact is first to engage and last to disengage itscorrespondingfixed contact, whereby unobstructed paths for the rise ofthe electric arcs are provided.l

6. An electric switch having a lurality of fixed contacts out ofvertical and) horizontal alinement having inclined flat faces arrangedin intersecting planes, an oscillatory carrier, a plurality of connectedflexible contacts affixed thereto at an angle to each other, the ends ofsaid contacts being beveled in intersecting planes with the longestflexible contact. uppermost., means for oscillating the morabie carrierinto andout of engagement u ith the fixed carrier, the fixed and movablecarriers being relatively so located that the uppermost member of eachmovable contact is first to engage and last to disengage itscorresponding 'fixed contact, whereby unobstructed paths for the rise ofthe electric arcs are provided.

7 A device of the character described comprising a main switch, anelectromagnet for closing the same, the movable element of said switchbeing connected to the armature of said magnet so as to be actuatedthereby, a latch for locking said switch closed, a selfclosing auxiliaryswitch in series with the closing magnet, mechanical means operated bythe closing movement of said armature for opening said auxiliary switchjust prior to complete closing of said main-switch, and means forholding said auxiliary switch uo en durin the o enino movement of the Pg P e.

main switch until the latter is nearly fully open, said holding meansbeing adapted to release the auxiliary switch when the main switch isfully open.

8. A device of the character described comprising a main switch, anelectro-magnet for closing the same, means for locking said switch inclosed position, a self-closing switch in series with said closingmagnet, means actuated by said closing magnet for opening saidself-closing switch during the closing movement of the main switch,saidopening means being ineffective until the main switch is nearlyclosed, and means controlled by the main switch for holding open theself-closing switch until the main switch is nearly open.

9. ,A device of the character described,

comprising a main switch, an electromagnet for closing the same, aspring-pressed latch' for locking said main switch closed, a selfclosingswitch for controlling the circuit through said closing magnet, meansactuated by said closing magnet for opening said selfclosing switchduring closing movement of the main switch, and a spring-pressedtriplatch carried by said self-closing switch, said locking latch havinga shoulder for coperating with said trip-latch whereby the selfclosingswitch is held open during the opening movement of the main switch.

10. A remote-control switch for electric lighting or power circuitscomprisi'n a rock shaft, movable contacts on said roc shaft, an armaturesecured at its lower end, to'said rock shaft, a stationary electromagnetin operative relation to said armature, stationary contacts forengagement by said movable contacts, a latch for locking said armaturein its closed position, and a solenoid on the outer face of saidarmature and arranged at an angle thereto with its core in position toengage said latch when the armature is closed, whereby when a circuit isclosed through said solenoid its core trips the latch and simultaneouslyforces the armature and the movable contacts to open position.

11. An electrical switch mechanism comprising stationary contacts, meansfor supporting said contacts with their faces in inclined intersectingplanes, the face of one member being below and to one side of the faceof the other member, movable laminated contacts arranged at an angle andhaving their ends beveled in intersecting planes, and means to whichsaid movable contact members are operatively connected and by whichtheir beveled ends are moved into and out of contact with the faces ofthe stationary contact members.

12. A device of the character described, comprising a main switch,electromagnetic means for closing the same, a controlling switch inseries with said means, means operative by the initial closing movementof the main switch for opening said controlling switch and therebyopening the circuit through said magnetic means before the main switchis closed', a pivoted latch for locking the main switch when it isclosed, means for movingsaid latch about its pivot to release the mainswitch, and means for holding the controlling switch open during theinitial opening movement of the main switch until the latter is nearlyopen.

13. In a device of the character described, a main switch,electromagnetic means for 100 closing theY same, a controlling switch inseries with said means, means forlocking the main switch inr closedposition, and trip mechanism for holding I the lcontrolling switch openduring the opening movement 105 of \the main switch, said trip mechanismbeing operative by the locking means for releasing the controllingswitch when the main 'switch is open.

VIn testimony whereof I have atiixed my 110 signature, in presence oftwo witnesses.

GRANVILLE E. PALMER.

